1. Field of the Invention
The present invention relates to a semiconductor light emitting device, and a method of fabricating such a semiconductor light emitting device. Particularly, the present invention relates to a semiconductor light emitting device employing a light emitting element such as an LED (Light Emitting Diode), and a method of fabricating such a semiconductor light emitting device.
2. Description of the Background Art
Semiconductor light emitting devices employing a light emitting element such as an LED are conventionally known.
For example, Japanese Patent Laying-Open No. 11-087780 (first conventional example) discloses a light emitting device including a light emitting element, a lead frame on which the light emitting element is to be mounted, a lead frame for electrical connection to the light emitting element via a wire, and a molding covering most of the lead frames. Respective lead frames are arranged opposite to each other, passing through the molding to project outside.
Japanese Patent Laying-Open No. 2001-185763 (second conventional example) discloses an optical semiconductor package including an optical semiconductor element, a lead frame on which the optical semiconductor element is to be mounted on the main surface, a first resin molding (lens) formed of light shielding resin, arranged so as to cover the optical semiconductor element, and a second resin molding (case) formed of light transmitting resin with a bottom supporting the inner lead of the lead frame and a side supporting the first resin molding. The lead frame is formed such that the region at the back side of the lead frame corresponding to the region where the optical semiconductor element is mounted penetrates the bottom of the second resin molding to be exposed outside, constituting a first heat dissipation region, and an outer lead portion constitutes a second heat dissipation region.
Japanese Patent Laying-Open No. 06-334224 (third conventional example) discloses a fabrication method of an LED light emitting device including the steps of attaching an LED chip to a printed board, arranging a pair of molds with respect to the printed board, and introducing synthetic resin for molding from a predetermined position that does not have an adverse effect on the lens characteristics in the mold located at the LED chip mounting face. The printed board has a through hole near the LED chip.
Problems of such semiconductor light emitting devices will be described hereinafter.
If the semiconductor light emitting element in the first conventional example becomes thinner, the depth of the bowl-like concave formed by the molding will be reduced, leading to a wider angle of radiation of the output light. There is a possibility of the adjustment of the directivity being partially degraded when the light emitting element is reduced in size.
The light emitting devices of the second and third conventional examples have a lens formed of transparent resin on a printed board or lead frame. Accordingly, the angle of radiation of the output light can be reduced to improve the axial luminous intensity.
When a lens is to be formed as in the second and third conventional examples, the height of the lens must be ensured such that the light emitting element (LED chip) and wire are covered. As a result, there are cases where reduction in the size of the light emitting element is restricted.
In the second conventional example, the lead frame is secured by the second resin molding. To ensure the strength of security, the second resin molding is made relatively large. As a result, there are cases where reduction in size of the light emitting element is restricted. It is to be noted that the third conventional example is silent about the concept of employing a lead frame.